const obj = {
    arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
    [Symbol.iterator]() {
        let index = 0;
        return {
            next: () => ({
                value: this.arr[index],
                done: index++ >= this.arr.length
            })
        }
    }
}

for (const item of obj) {
    console.log(item);
}